1. Field of the Invention
The present invention relates to methods for treating full range naphtha feedstock using a combination of distillation and hydrotreating to provide naphtha products with reduced sulfur content while minimizing reduction in octane number.
2. Description of the Related Art
Naphtha is a complex mixture of liquid hydrocarbons, which includes hydrocarbon molecules having between five and twelve carbon atoms and a boiling point range of about 30° C. to about 200° C. A number of process units produce naphtha product streams including, crude distillation, catalytic cracking, delayed coking and visbreaking units. These naphtha streams often are characterized by low octane numbers and the presence of different types of contaminants such as nitrogen, sulfur and oxygen containing molecules.
Refiners often subject naphtha streams to hydrotreating operations such as hydrodesulfurization in order to remove the nitrogen, sulfur and other contaminants that can reduce catalyst activity. A number of challenges associated with naphtha hydrotreating include maintaining an exclusively vapor phase across charge heaters leading to the hydrotreating reactor, avoiding excessive heating across the catalyst beds of the hydrotreating reactor, and mitigating reductions in octane number.
There is consequently a demand for new hydrotreating processes which can effectively address the aforementioned challenges. Ideally, the products of these processes, should have a sufficiently low sulfur content to meet applicable standards and have a sufficiently high octane number for use in gasoline blending.